How To Avoid Kahm Yeast
Kahm yeast is a type of wild yeast that can form a white, sometimes wrinkly or filmy layer on the surface of fermenting foods and beverages. It’s generally harmless but can affect the flavor and smell of your ferments. Here’s how to avoid kahm yeast during fermentation:
✅ Tips to Prevent Kahm Yeast
- Use the Right Salt Concentration
- Kahm yeast thrives in low-salt environments.
- Use the recommended salt levels for your ferment (typically 2–3% by weight of the vegetables or brine).
- Keep Oxygen Out
- Kahm yeast is aerobic and needs oxygen to grow.
- Use fermentation weights to keep vegetables submerged and lids or airlocks to minimize oxygen exposure.
- Maintain Clean Equipment
- Sterilize jars, utensils, and weights before use to reduce contamination.
- Use a Fermentation Lid or Airlock
- These prevent air from entering while letting gases escape, minimizing oxygen exposure.
- Keep Vegetables Submerged
- Any exposed vegetable matter can be a breeding ground for yeast and mold. Use fermentation weights or a cabbage leaf as a cover.
- Control the Temperature
- Ferment in a cool, stable environment. Ideal temperatures are usually 65–72°F (18–22°C). Warmer temps encourage kahm yeast growth.
- Monitor and Skim if Needed
- If kahm yeast appears, skim it off immediately. It won’t stop fermentation but can affect taste and smell if left unchecked.
- Use Starter Cultures (Optional)
- Adding a bit of finished brine from a previous successful ferment or a commercial starter can outcompete unwanted microbes.